X-ray Diffraction

Bruker D8Advance diffractometer.

The XRD lab deals with classic geological problems such as soil lithography and mineral phase identification, using two diffractometers, a Philips PW1730 and a Bruker D8Advance, with a 9 position sample changer which allows us to run batches of standard powder diffraction samples. The Bruker is fitted with a Göbel mirror which focuses the X-ray beam, giving us beam intensity comparable to first generation synchrotron. It is this beam intensity that allows us to perform reflectometry experiments, measuring the X-rays reflected from mineral surfaces to deduce surface roughness. We can also collect diffraction patterns from non-powdered samples, e.g. those too precious to powder, such as meteorites and archaeological samples.

Location: Room B.14 | Member of staff: Dr John Waters

XRD patterns of barite and barite + PVS.

Since the diffractometer is in theta-theta geometry, we can take further advantage of the precise control over sample height afforded us by the reflectometry stage to perform depth profiling of the surface 1-2 μm of samples, by varying the incident angle of the X-ray beam and hence the X-ray penetration depth.

These XRD patterns were collected using the PW1730. The patterns demonstrate that whilst the presence of PVS scale inhibitor during barite precipitation leads to widely differing morphology (shown in the accompanying SEM micrographs), the crystal structure is essentially the same, save for those changes in orientation, and hence peak intensity, which give rise to the shape of the particulates.

Our facilities are available for commercial use.

Mössbauer Spectrometer

Fastcomtec MCA-3 Mössbauer Spectrometer

This instrument is a Fastcomtec MCA-3 Mössbauer Spectrometer, with a 25 mCi Co-57 source and is equipped with a liquid N2 cryostat with temperature controller for experiments between 77K and 300K. Recoil commercial software is utilised for fitting of data.           

The spectrometer allows studies of the crystal chemistry of iron in minerals (oxidation state, spin state, co-ordination and covalence). Samples must be > 100mg of powder with at least 5% Fe content.  Samples will be mounted by staff. Powder samples can be mounted in a sealed anaerobic package.

Booking is strictly by arrangement with staff, experiments can only be run by staff/trained users.

 

Location: Room B14a, Williamson Building  |  Member of staff: Dr Paul Wincott

 

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